【求助】请教，高手讲解一下 2D IPAP [13C,1H] HSQC

A sensitivity-enhanced IPAP NMR experiment separates the 1H-15N doublets into two different spectra to alleviate the problem of resonance overlaps and achieve the accurate measurement of J and residual dipolar coupling constants in proteins. This experiment offered 20％-60％ sensitivity enhancement over the original IPAP experiment, and therefore produced more measurable resonances.Pulsed field gradient was used for coherence selection. Water-flip-back approach was used for water suppression. The sensitivity-enhanced IPAP experiment was employed in the measurement of 1JNH and 1DNH constants of the protein UBC9.